Question: If $7a + 7b = -8$ and $7x + y + 4z = 8$, what is $-4y - 16z + 14b - 28x + 14a$ ?
Explanation: $= 14a + 14b - 28x - 4y - 16z$ $= (2) \cdot (7a + 7b) + (-4) \cdot (7x + y + 4z)$ $= (2) \cdot (-8) + (-4) \cdot (8)$ $= -16 - 32$ $= -48$